Some Queens storeowners have their own brand of justice for sticky-fingered thieves: a wall of shame.

Flushing mom-and-pop stores that catch shoplifters red-handed seize their IDs and hold them hostage until the pilferers pay a $400 fine.

If the thieves don't cough up the cash, the shops threaten to plaster their faces right on the front door for everyone to see.

The public shaming is a popular deterrent at grocery stores in Chinese immigrant communities, local businesses said yesterday.

"We get shoplifted about three times a month, and the photos keep them from coming back. They don't show up again," said Lisa Wang, 34, manager of A&N Food Market, where pictures of suspected thieves decorated the front walls.

Experts say the practice - which has its roots in China and Taiwan - is illegal because only law enforcement agencies have the right to seize IDs after an arrest.

"You have a system that's outside the criminal and civil process," said Jim Cohen, a professor at Fordham University School of Law. "I think it is extortion, and it's made worse by the vulnerability of the population and the likelihood that they are unduly afraid about the [police] and being deported."

The Queens district attorney's office declined to comment on whether the practice breaks the law. The NYPD said it has not received any complaints.

Assemblywoman Grace Meng, who represents Flushing, said some shopkeepers go around cops because they don't speak English well and fear that involving the law will slow down business.

"In some Asian communities, especially in Flushing, a storeowner somehow informing their own community can even be more shameful than informing police," Meng said.